Discussion Forum

Hi. I'm very new to COMSOL. I want to calculate thermo-poroelastic deformation in 2-D axissymmetric cylinder.

I have three questions. (1) How can I import values in a text file as format of [ x, z, value ] (value is change in pore pressure or change in temperature at each grid). Change in pore pressure and temperature were calculated beforehand by TOUGH2, which is a famous fluid flow simulator.

(2) How can I assign imported values into each mesh element.

(3) How can I implement stress tensor, including terms of thermomal expansion and pore-pressure-induced expansion (below formulation), at each mesh element.

stress(i j) = λ* (volumetric strain)δ(ij) + μstrain(i j) + βΔPδ(ij) + αKΔT*δ(ij)

i, j    : component index

δ(ij) : Kronecker delta β : Biot-Willis coefficient α : thermal expansion coefficient K : bulk modulus

 ΔP  : pore pressure change     (input from text file whose format is [x, z, ΔP] )
 ΔT  : change in temperature   (input from text file whose format is [x, z, ΔT] )

I tried using diagonal "External stress" in "Structure Mechanics" module, but I couldn't find how to assign different ΔP & ΔT value at different element.

Next, I tried implenting thermo-poroelasicity using general form PDE module. However, coservative flux term (Γ), which corresponds to stress, cannot be defined detailed anymore (I want to make the constitutive ralation of thermo-poroelasticity described in above equation).

Thank you in advance.